Bank of switch keys



May 7, 1940. T COOPER 2,200,076

BANK OF SWITCH KEYS Filed Dec. 30, 1938 2 Sheds-Sheet 1 flawlalfapcr W Gttorncg May 7, 1940. D. T. COOPER BANK OF SWITCH KEYS 2 Sheets-Sheet 2 Filed Dec. 30, 1938 Patented May 7, i940 UNITED STATES BANK OF SWITCH KEYS Donald '1'. Cooper, Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application December 30, 1938, Serial No. 248,562

5 Claim.

This invention relates to banks of switch keys the plunger or push-button type, and has for its principal object to provide a bank of switch keys which is susceptible of more than one mode of operation.

Banks of switch keys of the push-button or plunger type are known wherein any push-button that is depressed is automatically locked in depressed position, the depression of any other m push-button of the bank releasing the first depressed push-button, the last depressed push- Ioutton being automatically locked in depressed position until released by the depression of another push-button present invention contemplates and its practice provides a bank of switch keys which includes two master or control keys. The master are so arranged with respect to the other keys that upon the depression of the first master key the hauls may be operated in the manner above described. The depression of the second master key serves to clear the bank and also to so change its mode of operation that any desired number of keys may be depressed and locked in 25 the depressed position until released by the depression of the first master key. Each master key may have a switch element individual thereto, in which case, when the bank is operated under the control of the first master key, the switch 30 individual thereto will be maintained in its actuated position (on or off, as the case may be) irrespective of the releasing action of any of the keys other than the second master key.

While the invention will be described as embodied in apparatus for testing electron-discharge devices (e. g., radio tubes) it is to be understood that the disclosure lnthis respect is merely illustrative forthe purposes of explaining the inventive concept.

40 In the drawings:

Figure 1 is a view in perspective of an apparatus for testing radio tubes, showing a bank of switch buttons wherein the left-hand and the right-hand buttons comprise the master keys,

Figure 2 is a fragmentary front-elevational view of a switch bank constructed in accordance with the principle of the invention and while operated under the control of the right-hand master key of Fig. 1,

Figure 3 is a rear elevation of the switch bank of Fig. 2 operated under the control of the same master key,

Figure 4 is a fragmentary rear elevational view of the switch bank of Figs. 2 and 3 but operated 55 under the control of the other master key,

Figure 5 is an end elevation looking in the direction of the arrow Ii in Fig. 3,

Figure 6 is an end elevation looking in the direction of the arrow 6 of Fig. 3,

Figure 7 is a sectional elevation taken on the 5 line 1-1 of Fig. 4,

Figure 8 is a sectional elevation taken on the line 8-8 of Fig. 4,

Figure 9 is a front elevation of a latch bar which is operated by the master keys, 10

Figure 10 is a front elevation of a latch bar operated by the other switch keys, and

Figure 11 is a fragmentary rear elevational view of an alternative embodiment of the invention. 15

The portable tube-tester shown in Fig. 1 is designed to test radio tubes according to present R. M. A. (Radio Manufacturers Association) standards. The device illustrated comprises a box-like container I having an inclined panel 2 to which is secured a plurality of tube sockets 3 designed to jointly accept any oi the several hundred electron and ballast tubes now on the market. The tubes 'are tested in accordance with test information contained on a rolled chart 4. 2 The data contained on the chart and individual to the various types of tubes is viewed through a window 5 as the sections of the chart are moved in register with the window under the control of a hand wheel 6. Other more or less conventional parts of the test equipment comprise a cable I, a line switch 6, a neon lamp 9. a meter I 0, a line voltage control H, a filament voltage regulator 12, a. change circuit or class switch I 3, a calibrated meter potentiometer or type 5 switch It, and a plurality of push-buttons designated 2i to 3|, inclusive.

As will hereinafter more fully appear, the end buttons 2! and 3|, respectively, are master buttons which control the mode of operation .of 40 the switch bank of the invention. The center button, 1. e., the one numbered 26, may be designated the output button as it is designed to change over the meter circuit from measuring line voltage, when it is in its normal or raised position, to measuring tube output current when it is depressed. The button 26 is designed to be operated entirely independently of the operating position of the other buttons Two general classes of tests may be made with the device of Fig. 1. One class of test is calculated to reveal defects due to short circuits within a tube; a shorted circuit being indicated by the glow lamp 9. The other class of test is concerned, in the absence of a "short, with the 56 quality or output characteristics of the tube and as manifest by reading the meter l0. Each class of test may require the manipulation different combinations of the buttons 2| to 3|, inclusive. By way of example, the test for shorts" usually requires that but two buttons, say, 2| and 22 or 2| and 23 or 2| and 21, etc., be in the depressed position at any given movement while the quality test may require that two, three, four or more buttons be depressed at the same time. Heretofore this has made it necessary for the operator to employ both hands or at least several fingers of one hand, in making the several tests. When the buttons are connected to a bank of swiches which has been constructed in accordance with the present invention all tests under control of the button may be conducted by the use of but a single finger, leaving the operator's hands otherwise free to manipulate the other control elements, to record the results of the tests, or to make ready other tubes.

In the interests of clearness and completeness, a brief description will be given of a preferred manner of operating the tube tester of Fig. 1 before proceeding with a detailed description of the switch banks employed therein, and which comprise the invention. In operating the device of Fig. 1, the cable 7 is connectedto a 100-125 volt 50-60 cycle line and the line switch 8 turned on. The meter ID will be understood to be calibrated to read line volts and is suitably adjusted by means of the line-voltage control The chart 4 is rotated by means of the hand-wheel 6 until test information specific to the tube to be tested is in register with the window 5. The filament voltage control l2, the "class switch |3 and the type control M are then adjusted to the position indicated on the chart. These latter adjustments are rendered simple by reason of the provision of connecting lines (indicated at |5, |6 and I1) connecting the several controls to corresponding columns on the chart. With a tube (not shown) in the correct socket the short test is preferably the first to be conducted. To conduct this test, the first button, i. e., button 2|, is depressed and is thereby automatically locked in the depressed position, then buttons 22 to 30, inclusive, (or some of them as indicated by the chart) are depressed preferably in the order of their numbers. The depression of any of these buttons 22 to 30, inclusive, and which will occasionally be referred to as selector buttons, releases any previously depressed button, other than button 2|. If, during the test just described. lamp 9 glows, a short circuit is indicated and the tube may be discarded unless the chart indicates that a short is normally present in the tube under test. On the other hand, if a short circuit is not indicated the switch bank is made ready for the quality test by depressing the mas-' ter button 3| which releases both the master button 2| and also the last depressed of the selector buttons 22 to 30, inclusive.

When the master button 3| is depressed, it is automatically locked in the depressed position. The chart informs the operator as to which selector buttons must then be depressed for the quality test. The lines I8 leading from the chart to the buttons direct the operator to the current buttons. By way of example, the chart may dictate the use of selector buttons 23, 25, 21 and 29, or some other combination of two or more buttons including the master button 3| but not including the master button 2|. In this case each button in the combination is automatically locked when depressed and the depression of one selector button in no wise disturbs the other buttons in their locked position.

Referring now to Figs. 2 to 10, inclusive. The push buttons 2| to 3|, inclusive, of Fig. 1 are attached respectively to the similarly numbered switch keys or plungers of Figs. 2 to 10 inclusive. As shown more clearly in Fig. 8 each plunger comprises a central body or key portion a, which has a central rectangular slot b therein, and a pair of arms 0, :2, respectively, which extendln opposite directions from the key portion a through aligned orifices in the top and bottom slats 32, 33, respectively, of a rectangular frame. Each plunger is biased to return to its idle or raised position as by means of a coiled spring S which surrounds its lower arm d and rests upon the inner surface of the bottom slat 33 of the frame. A piece e of felt, soft rubber, or the like, fitted about the upper arm 0 of each plunger serves to cushion the impact of the key portion (1 against the upper frame slat 32 when the plunger is returned to its idle position by the biasing force of the spring S. A piece of insulating material j inserted in notches g. which are provided for the purpose on an edge of the key portion of each plunger, carries one or more switch elements it (see Fig. 2) which, in the case of plungers 2| to and 21 to 3| comprises the movable contact of a double pole single throw switch and, in the case of the plunger 26, comprise the movable contacts 72, h of a double pole double throw switch. Referring to the frontview of the switch bank, as shown in Fig. 2, the fixed switch contact elements 9', k and m are mounted upon an insulating strip or plate 34 which may be conveniently anchored to the frame as by eyelets which are secured to the sides of a pair of upstanding end pieces 36, 31, on the frame. If necessary or desirable, other fixed and movable elements of any suitable type of switch may be mounted adjacent the opposite or rear major side of the frame. Circuit connections. not shown, are made to the fixed contacts 9', k, m, as by soldering or otherwise.

It is obvious that unless some locking or holding force intervenes, the several plungers will be returned by the springs S to their idle or raised position when the force which depresses them is released.

Referring particularly to Fig. 3, it will be observed that the selector plungers 22 to 25 inelusive and 21 to 30 inclusive each have a strip of spring material T ailixed thereto as by a single rivet n on the lower arm d. These spring strips T, like the key portions a of the plungers. have rectangular slots therein (see Fig. 8). They are of somewhat shorter length, however, and are each provided at the upper end with a lip or catch t which extends into and across the slot in the key portion of the plunger. Since these catches t are at the free ends of the spring strips T, they are adapted to be pivoted outwardly about n as a center when the strips T are flexed. The end plungers 2| and 3| do not have spring catches thereon, but instead are each provided with an inflexible cross bar or catch t" (Fig. '7) which spans the slot 12 in the key section preferably at the same relative height or position as the spring catches on the other plungers. 'I'he central plunger 26 is slotted but has neither a flexible nor inflexible catch thereon since, in the instant embodiment of the invention, this meter plunger is designed to be operated entirely independently of the other plungers.

A pair of latch bars which are designated 39, 40, respectively, in Figs. 3, 5, 9 and 10 extend through the central slots in the plungers and spring strips. These latch bars 39 and 40 are supported on the end pieces 36 and 31 of the frame for independent movement in a path normal to the path of the plungers. Referring to Figs. 3 and 10, it will be noted that the latch bar 40 is provided with a latch L individual to each plunger, except plunger 23. The other latch bar 39 (Fig. 9). is provided with but two latches M, one on each end, for engagement with, the inflexible catches on plungers 2| and 3|; respectively. The latches M, on bar 39 are in register with the latches L, on bar 40 so that the in-,

flexible catches (t') on the end plungers 2| and 3| may simultaneously engage a registered pair of these end latches.

The latch bars 39 and 40 are independently biased by end springs W and V, respectively, for movement in the same direction, i. e., to the right as viewed in Figs. 3 and 4. As shown at the left ends of Figs. 3 and 4 and in Fig. 5, spring W has the general form of the letter W and is anchored at its free ends to the end piece 31 of the switch frame. Its biasing force is applied to the end of latch bar 39 through the central bowed part of the W. An end section of the latch bar 40 adjacent the point of contact of this spring is cut away as indicated at at (Figs. 3, 4, 5'

and 10) to prevent the spring W from exerting any biasing force against bar 40. As shown in Figs. 3, 4 and 6, the coil spring V exerts its biasing force outwardly from the opposite end of the frame against a washer 1) which is fixed on the end of latch bar 40. Since washer v is fixed only on bar 40, the biasing force of spring V in no wise affects the other latch bar 39.

As previously described, the end latches M on bars 39 are normally in register or aligned respectively with the end latches L, of bar 40. Therefore, when plunger 3| is depressed, its rigid catch t will ride on the inclined top surface of both latches L and M and move both of the latch bars 39, 40 in the direction opposite to the direction of their bias. As the catch t rides on the lower end of these latches L and M, the springs Wand V urge the latch bars to the right so that the catch engages both latches. The latch bars may now be said to be in substantially the position normally dictated by the force of their biasing springs W and V. In order to lock the latch bars 39, 40 in the said position, a bent spring Y is provided on the master plunger 3| so that, when the plunger is depressed, the force of this lock spring Y is applied to'and adds its force to bar 40 in the same direction as the force applied to that bar through spring V.

The tension or biasing force of the lock spring Y is preferably several times greater than that of the catch springs T. Therefore, when plunger 3| is depressed and the force of the lock spring Y applied to latch bar 40 the'subsequent depression of one or more of the selector plungers 22 to 30 inclusive, will not move the bar 40 but will cause the spring catch on the depressed plunger to flex outwardly about the point n and to ride over the inclined surface of the latch and to engage the notch on the underside of the latch, thereby holding it in the depressed position. As shown in Fig. 3, when plunger 3| is depressed to engage the lock spring Y the subsequent depression of any desired number of the selector plungers 22 to 25, 21 to 30 will cause them all (in this case, plungers 29 and 20) to be automatically locked in the depressed position.

As previously brought out and as shown in Fig. 7, the master plunger 2| is provided with an inflexible catch t. Consequently, when plunger 2| is depressed, a moving force is applied to both latch bars 33 and 40 as the right catch rides on the inclined surfaces of the aligned latches of L and M. The force thus applied to the latch bars 39 and 40 moves them to the left (as viewed in Figs. 3 and 4) and, as shown in Fig. 4, releases the lock spring Y and disengages the latches L and M which held the other master plunger 3| in the depressed position. Releasing the lock spring Y restores control of the movement'of the latch bars 39 and 40 to the biasing springs W, V, individual thereto, so that both of the latch bars are moved in the return direction (i. e., to the right, as viewed in Figs. 3 and 4) causing the momentary movement of latch bar 40 will re--.

lease any previously depressed plunger (except the master plunger) which is then returned to the raised or idle position by its coil spring S. As soon as the catch on the last depressed selector plunger 22 to 25, 21 to 30 has passed over the inclined surface of its latch L, the biasing spring V shifts the latch bar 40 to the right whereby the latch thereon engages the catch on the said plunger and holds it in the depressed position until it is released by the subsequent depression of another plunger.

. If the next plunger to be depressed is the master plunger 3| the rigid catch it thereon applies a moving force to both of the latch bars 39 and 40, since, as previously brought out, the end latches M and L are aligned with each other. Obviously, the movement of both latch bars simultaneously (to the left, as viewed in Fig. 4) releases the master plunger 2| as well as the last depressed of plungers 22 to 25, 2'! to 30.

In the interest of compactness, it is desirable that both latch bars be arranged closely adjacent each other as in the manner described in connection with the switch bank of Figs. 2 to 10, inclusive. It is not necessary, however, that they be thus arranged. They may be arranged one under the other, for example, as in the embodiment of the invention shown in Fig. 11. The separate latch bars are here designated I39 and I40, respectively. Each plunger I2I to I3I except the center meter plunger I26 is provided with two catches t and t respectively, the one (if for engagement with the upper latch bar I40 and the other (t for engagement with the latches on the lower latch I39. The latches for the catches of the selector plungers I22 to I25 and I2'I to I30 are in the form of bowed springs I 50, and the latches for the catches on the master plungers I2I and I3I comprise simply the end surfaces of the orifices in the latch bar I39 through which the plungers I2I and I3I extend. The depres sion of the master plunger I 3| moves both latch bars I39 and I40 to the left and the biasing springs W, V thereon cause a return movement on both latch bars which causes the latches to engage the catches on the plunger Ill. With the plunger I3I depressed, two or more of the selector plungers I22 to I25, I21 to I30 may be depressed and be locked in the depressed position since the force of spring V' holding the lower latch bar I39 in its extreme right-hand position is greater than the force required to flex the bowed latch springs I50.

When the other master button III is depressed both latch bars are moved to the left thereby releasing or clearing the previously depressed buttons including the master button I3I. Upon completion on this movement to the left, both bars are returned to the right by the force of their biasing springs W, V. This movement of the lower latch bar I39 to the right is not as extensive as the corresponding movement when the master plunger I3I is depressed because the lower catch on plunger I2I is not as deep or cut away as much, as the lower catch on plunger I3I. When in this position the spring latches I50 are held to the left of the path of the catches and will therefore not engage them. Since the upper latch bar I40 is always moved to the left upon the depression of any plunger (except the center plunger I26) the depression of one plunger will release the last depressed plunger, other than the master plunger I2I which is held depressed by the lower latch bar I39.

The two embodiments of the invention herein described are susceptible of various modifications which will be apparent to those skilled in the art. It is to be understood therefore that the disclosure is to be interpreted as illustrative and not in a limiting sense except as required by the prior art and the spirit of the appended claims.

What is claimed is:

1. A bank of switch keys comprising a plurality of selector plungers and a pair of master plungers, a pair of latch bars mounted for independent movement in paths which intersect the paths of movement 01 said plungers, means for separately biasing said latch bars, complementary catch members on each of said plungers and latch bars, means responsive to the depression of one of said master plungers for moving one of said latch bars against the force of its bias to a position whereat the catch members individual thereto are maintained in engagement with complementary catch members on all subsequently depressed of the selector plungers, means responsive to the depression of the other of said master plungers for moving said latch bar out of engagement with the catch members on said previously depressed plungers, and means operative while the said other of said master plungers is in its depressed position and comprising the other of said biased latch bars for locking any one of said selector plungers in depressed position until the subsequent depression of another plunger.

2. A bank of switch keys comprising a plurality of plungers, a spring catch on individual of said plungers, a pair of latch bars mounted for movement in a path normal to the path of said plungers and having latches thereon adapted to engage said spring catches, means for separately biasing said latch bars, means responsive to the depression of one of said plungers for locking said latch bars in the position normally dictated by the force of their biasing means and whereat said latches are in a position to engage and to hold'said spring catches when the plungers individual thereto are depressed, and means responsive to the depression of another of said plungers for moving said latch bars against thr force of their locking and biasing means whereby to release all of the previously depressed plungers and to return the control of the movement of said latch bars to the force of their biasing means.

3. A bank of switch keys comprising a plurality of selector plungers and a pair of master plungers, an inflexible catch on each of said master plungers and a flexible catch on each of the selector plungers, a pair of latch bars mounted for independent movement in paths which intersect the paths of movement of said plungers. one of said latch bars having latches thereon adapted to engage both the flexible and inflexible catches and the other of said latch bars having latches thereon adapted to engage only the inflexible catches, means for separately biasing said latch bars, the biasing force applied to said first-mentioned latch bar by its biasing means being less than that applied to said latch bar by any one of said spring catches when the selector plunger upon which said spring catch is mounted is depressed, whereby the depression of one of said selector plungers normally operates to move the flrst mentioned latch bar against the force of its bias, to release any previously engaged spring catch and to engage the spring catch on the last depressed selector plunger, means responsive to the depression of one of said master plungers for applying an additional biasing force to said first-mentioned latch bar, the combined force applied to said latch bar when said master plunger is depressed being greater than the force applied thereto by a spring catch when its plunger is depressed whereby any desired number of said selector plungers may be depressed and automatically locked in depressed position, and means comprising the inflexible catch on the other of said master plungers for applying suiiicient force to said first-mentioned latch bar to move it against the total biasing force applied thereto when said first-mentioned master plunger is depressed, whereby to release all of the previously depressed plungers and thereby restore said device to its said normal mode of operation.

4. A bank of switch keys comprising a pinrality of plungers including a pair of master plungers, a pair of catches on each of said plungers, a pair of latch bars mounted for inde pendent movement in paths which intersect the paths of movement of said plungers, one 01' said latch bars having inflexible latches thereon individual to one catch of each master plunger and a plurality of spring latches individual to one catch on each of the other of said plungers, and the other of said latch bars having inflexible latches individual to the other catch on each plunger, means for separately biasing said latch bars, means responsive to the depression of one of said master plungers for moving the first mentioned latch bar to a position whereat the flexible and inflexible latches thereon are in a position to be engaged and held by one catch on each plunger when the respective plungers are depressed whereby any desired number of said plungers, not including the other master plunger, may be depressed and automatically locked in the depressed position, means including one of the catches on said other master plunger for moving said latch bar against the force of its biasing means from said position to ISO a. position whereat the previously engaged of T6 the latches thereon are out of the path of the other of said plungers whereby all of the previously depressed plungers are released and the sole force retaining any subsequently depressed plunger other than the first mentioned master plunger in a depressed position comprises the biasing force applied by said second mentioned latch bar to the catch in the path thereof.

5. A bank of switch keys comprising a plurality of selector plungers and a pair of master plungers, a pair of latch bars mounted for independent movement in paths which intersect the paths of movement of said plungers, means for individually biasing each of said latch bars, catches on each of said master and selector plungers, complementary latches for said catches upon said latch bars, means responsive to the depression of one of said master plungers for moving both said latch bars against the force of their biasing means to a position whereas a catch on said master plunger engages a latch on each of said latch bars and whereat the other latches on one of said latch bars are in position to be engaged by the catches on each selector plunger, means responsive to the depression of the other of said master plungers for moving 'said latch bars out of engagement with the catches on all of said previously depressed plungers and into engagement with said latest depressed master plunger, and means including said biasing means and operative while the said other of said master plungers is in its depressed position for locking anyone of said selector plungers in its depressed position until the subsequent depression of another plunger.

DONALD T. COOPER. 

